1. Technical Field
This invention relates to input devices for computers and the like, and more particularly to a system and method for providing 3-D input in real time.
2. Background Information
Throughout this application, various publications, patents and published patent applications are referred to by an identifying citation. The disclosures of the publications, patents and published patent applications referenced in this application are fully incorporated by reference into the present disclosure.
A wide variety of devices are capable of wirelessly controlling the movement of a cursor or other on-screen display element. For example, U.S. Pat. Nos. 5,847,710 and 6,380,732 both disclose systems capable of capturing the 3-D position of a passive (unpowered) implement by generating electro-magnetic (EM) fields, and then detecting disruptions therein caused by movement of the implement therethrough. A drawback of
this approach is that EM fields are susceptible to interference, and may generate unwanted interference. Other approaches, such as disclosed in U.S. Pat. Nos. 6,791,531, and 6,738,044 disclose systems that also utilize passive implements, but without the need to generate EM fields. Rather, these systems rely on reflective schemes, in which the position of the implement is determined by transmitting a signal towards the implement, and then measuring characteristics of the signal reflected therefrom. These patents, however, are relatively complex, may be susceptible to slight changes in reflection angle, and do not teach the capture of 3-D position data.
U.S. Pat. No. 5,757,360 and EP 1,035,481 both disclose active implements, i.e., powered implements that directly transmit signals. These references, however, rely on the use of accelerometers, and as such, are only capable of indirectly determining position, which tends to adversely affect accuracy thereof. For example, indirect methods that rely on a previously calculated measurement, can drift further and further from their actual value simply due to digital math approximation error.
U.S. Pat. Nos. 5,875,257 and 6,801,231 (the '257 and '231 patents) disclose systems intended to capture the position of an active implement that transmits signals which are then detected by stationary detectors. The '257 patent uses one or more lenses and Position Sensitive Photodiodes (PSDs), devices which inherently detect and report two-dimensional position data of light spots or distributions incident on their detecting surfaces, and does not teach the manipulation of on-screen objects such as cursors and the like, while the '231 patent triangulates ultrasonic signals received at three distinct locations, projecting them to derive 2-D planar position data for controlling an onscreen computer cursor.
Thus, a need exists for a system and method for directly determining the 3-D position of a computer input device in real time.